MIST meeting
26 November 1999

Geological Society Lecture Room, Burlington House, London (enter from Piccadilly)

[Report published in Astronomy & Geophysics 41, 1.29-1.30 (February 2000)]

A. Programme B. Report C. Abstracts

MIST meeting, London, Autumn 1999

Coffee (served in the Library)

First session - Chairman: Dave Neudegg (Leicester)

I Krauklis (MSSL), O Vaisberg (MSFC) and B Petersen (Lockheed), Preliminary observations of magnetosheath plasma in the mid-altitude cusp by the Polar/TIMAS and Interball Tail/SCA1 experiments during an interval of strongly northward interplanetary magnetic field
J Rae, M Lester (Leicester), J Scudder (Iowa), M Grande (RAL), T Fritz (Boston) and C T Russell (UCLA), Pulsed cusp particles and their ionospheric flow signatures
T J Stubbs, P Cargill (IC), M Grande, B Kellett, M Lockwood and C Perry (RAL), Observations of the northern polar cusp with the Polar spacecraft
M Taylor and P Cargill (IC), A model of magnetic fluctuations in the cusp
S Oughton (UCL), W H Matthaeus, G P Zank, D J Mullan and P Dmitruk (Bartol), Alfvén waves + 2D turbulence = coronal heating?
W P Wilkinson (Brighton), A R Breen, P J Moran, C A Varley and P J S Williams (Aberystwyth), The Rankine-Hugoniot relations and co-rotating interaction regions in the solar wind
M Y Gulamali and P Cargill (IC), A multiresolution analysis of the solar wind magnetic field using the Wavelet Transform
S Dalla and A Balogh (IC), Recurrence in MeV proton fluxes and anisotropies at 5 AU from the Sun
M Hopcroft and S C Chapman (Warwick), 2D hybrid simulations of the solar wind interaction with a small scale comet
R Bamford, C J Davis, L Cander and L Farr (RAL), First results of measurements of the ionosphere during the 1999 total solar eclipse
E M Clarke (Hallam), C J Davis, M Lockwood, S A Bell and J A Smith (RAL), Ionospheric measurements of relative coronal brightness during total solar eclipses
T B Jones, T K Yeoman, T D Reid and P J Chapman (Leicester), Did the total eclipse of 11th August 1999 produce Atmospheric Gravity Waves?
A J Smith (BAS), MIST announcements
Lunch (available in the Library)

Second session - Chairman: Malcolm Dunlop (IC)

N J Mitchell, P J S Williams (Aberystwyth), T R Robinson (Leicester), S Kirkwood (SISP), D Pancheva and H R Middleton (Aberystwyth), A new VHF radar at Esrange to study mesosphere/lower-thermosphere region coupling and dynamics
A M Smith and L Kersley (Aberystwyth), Possible polar-patch formation; a multi-instrument case study
A Canals, A Breen, P Moran and R Fallows (Aberystwyth), Bulk flow speed and Alfvén wave flux in the fast solar wind
R Wilson and M K Dougherty (IC), Evidence of low frequency waves in Jupiter's middle magnetosphere
S A Espinosa and M K Dougherty (IC), Periodic perturbations in Saturn's magnetic field
R E Lowe and D Burgess (QMW), Shock structure and its effect on electron acceleration in Quasi-Perpendicular shocks
S E Pryse (Aberystwyth), Multi-instrument study of magnetopause reconnection footprints in the summertime ionosphere
K A McWilliams and T K Yeoman (Leicester), Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event
N V Nastasyina-Beloff (Sussex) and P.F. Denisenko (Rostov), The resolving power of the ionospheric radio sounding methods
Tea (served in the Library)

Third session - Chairman: Peter Cargill (IC)

D M Willis (Warwick) and F R Stephenson (Durham), Solar and auroral evidence for an intense recurrent geomagnetic storm during December in AD 1128
W J Wykes, S C Chapman and G Rowlands (Warwick), Enhanced phase space diffusion due to chaos in relativistic electron-whistler mode wave particle interactions
T K Yeoman (Leicester), R V Lewis (Ipswich), H Khan (Leicester) and J M Ruohoniemi (APL), Interhemispheric observations of nightside ionospheric electric fields in response to IMF Bz and By changes and substorm pseudobreakup
H Khan and S W H Cowley (Leicester), Effect of the IMF By component on the ionospheric flow overhead at EISCAT: Observations and theory
M H Denton, G J Bailey (Sheffield), R A Heelis and M Hairston (UTD), DMSP observations - electron temperature, ion temperature, density and concentrations. Results from 0900 LT Jan-Jun 1991
J K Hargreaves (Lancaster) and P N Collis (EISCAT), Spectrum and dynamics of a weak, night-time precipitation event observed by EISCAT in October 1996
A J Coates, D R Linder, A M Rymer (MSSL), M Grande (RAL), K Svenes, B Narheim (NDRE), D T Young (Michigan) and the CAPS team Cassini electron spectrometer observations during the 18 August 1999 Earth swingby
R H A Iles, A D Johnstone, A N Fazakerley and P Bühler (MSSL), Relativistic electron flux enhancements in the outer radiation belt
A Lawrence, M Jarvis, M Rose, M Clilverd (BAS) and M Taylor (USU), Implementation of an airglow imager in Antarctica
D Rees (USU/Hovemere), M Conde (Alaska), U Brandstrom and A Steen (SISP), Daytime ground-based optical imaging of the aurora

Affiliation abbreviations:

Aberystwyth: Prifysgol Cymru, Aberystwyth
Alaska: University of Alaska, Alaska, USA
APL: Applied Physics Laboratory, John Hopkins University, USA
Bartol: Bartol Research Institute, University of Delaware, USA
BAS: British Antarctic Survey
Boston: Boston University, USA
Brighton: University of Brighton
Durham: University of Durham; Dept. of Physics
EISCAT: EISCAT Scientific Association, Kiruna, Sweden
Hallam: Sheffield Hallam University
Hovemere: Hovemere Ltd, Bromley, Kent
IC: Imperial College, London; Space & Atmospheric Physics Group
Iowa: University of Iowa, USA
Ipswich: Ipswich School
Lancaster: University of Lancaster; Engineering Dept.
Leicester: University of Leicester, Radio and Space Plasma Physics
Lockheed: Lockheed-Martin Space Sciences Laboratory, USA
Michigan: University of Michigan, USA
MSFC: Marshall Space Flight Centre, USA
MSSL: Mullard Space Science Laboratory
NDRE: Norwegian Defence Research Establishment
QMW: Queen Mary and Westfield College, London; Astronomy Unit
RAL: Rutherford Appleton Laboratory
Rostov: Rostov State University, Russia
SISP: Swedish Institute of Space Physics, Kiruna, Sweden
Sheffield: University of Sheffield; Department of Applied Mathematics
Sussex: University of Sussex; Space Science Centre
UCL: University College, London
UCLA: University of California at Los Angeles, USA
USU: Utah State University, USA
UTD: University of Texas at Dallas, USA
Warwick: University of Warwick; Space and Astrophysics Group

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MIST meeting, 26 November 1999
Meeting Report

by N F Arnold (University of Leicester)

Published in Astronomy & Geophysics 41, 1.29-1.30 (February 2000)

The annual one-day meeting of the MIST (Magnetosphere, Ionosphere and Solar-Terrestrial) community was held on 26 November 1999 at the Geological Society, Burlington House. The organizer, Andy Smith (British Antarctic Survey), managed once again to pour a quart into a pint pot with 31 presentations over a wide range of topics without the schedule feeling overly rushed. The morning session was chaired by David Neudegg (Leicester) and began with four talks that concerned the Earth's magnetospheric cusp region between open and closed field lines. A combined Interball/Polar satellite study was described by Ian Krauklis (Mullard Space Science Laboratory) during high solar wind and northward Interplanetary Magnetic Field (IMF) conditions. Whilst the former was observing a lobe reconnection, the magnetosphere had been distorted such that the latter found itself within the cusp region. Jonny Rae (Leicester) combined results from Polar with ground-based observations from the CUTLASS Finland radar. Observations of 2-10 minute pulsations in the cusp region as measured by the spacecraft particle detectors could be related to pulsed ionospheric flows at the time of flux transfer events. Tim Stubbs (Imperial College) carried out a statistical study of Polar observations of the Northern Hemisphere cusp region. He found that the weak relationship between high solar wind speeds, the strength and direction of the vertical component of the IMF and the duration of expanded cusp conditions suggested that tail lobe reconnection was not the principal mechanism previously assumed. To complement the reporting of observational studies, Matt Taylor (IC) followed by describing a model of the interactions between low frequency waves and a cusp-like field geometry. Damping within the system suggested localized in situ source mechanisms. Additional processes were needed in the cusp to identify potential candidates.

Sean Oughton (University College London) presented a model of the Sun's outer atmosphere based on the driving of quasi-two-dimensional magnetohydrodynamic turbulence by low frequency Alfvén waves generated close to the photosphere. This mechanism may account for the much hotter corona compared with the photosphere. The next two talks dealt with the co-rotational interaction region within the solar wind. Will Wilkinson (Brighton) used the Rankine-Hugoniot relations that determine the physical parameters on both sides of MHD discontinuities to demonstrate that shocks with high Mach numbers can exhibit a well-defined rotation. Observations by the Ulysses spacecraft of these regions were reported by Murtaza Gulamali (IC). Fluctuations in the measured magnetic field were analysed using multi-resolution decomposition, revealing large structures with time scales of many hours and shorter scales characteristic of MHD turbulence. Silvia Dalla (IC) analyzed proton fluxes at around 5 AU using the Anisotropy Telescope on board Ulysses. A recurrent pattern emerged with a delay between events increasing from 122 to 155 days, possibly connected to the 154-day periodicity in the rate of solar flare occurrence. Matt Hopcroft (Warwick) presented 2-D simulations of super magnetosonic solar wind interactions with a small-scale comet. The bow shock structure was found to be sensitive to the flow Mach number and at high values generated a deflected velocity layer behind the shock.

The final three talks of the morning focussed on the opportunities presented by the total solar eclipse over Cornwall on 11th August 1999. Ruth Bamford (Rutherford Appleton Laboratory) reported nationwide efforts from the scientific community and the general public to gather a comprehensive and unique ionospheric record of the event. Large changes in radio signals were reported due to a significant reduction in the electron density. Ionosonde observations in Cornwall were described by Elizabeth Clark (Sheffield Hallam) to estimate the flux of ionizing radiation during the eclipse. She compared the recent eclipse with a similar event in July 1945 and noted significant differences that might be due to structural changes in solar activity. Finally, Tudor Jones (Leicester) discussed a number of experiments carried out to search for acoustic gravity waves within the thermosphere around the time of the eclipse. There was an unusual abundance of such disturbances on the day and waves with a direction of propagation consistent with a source region close to the path of totality were observed.

The first session of the afternoon was chaired by Malcolm Dunlop (IC). One of three consecutive speakers from Aberystwyth, Nick Mitchell described a new meteor radar system that has recently been deployed at Esrange in Sweden to monitor the dynamics of the upper mesosphere and lower thermosphere on a continuous basis. New interferometric techniques allow a vertical resolution of 2 km and a time resolution of an hour to be obtained. Defense Meteorological Satellite Programme data was combined with a network of high latitude radars by Adam Smith to investigate the progress of enhanced ionospheric density structures. He proposed that these were related to changes in the configuration of the IMF. Alison Canals analyzed European Incoherent Scatter radar interplanetary scintillation measurements of fast stream solar winds to identify signatures of the dissipation of low frequency Alfvén waves. Such a process has been proposed as a mechanism for accelerating the solar wind.

The next two talks took the audience to the Outer Planets. Rob Wilson (IC) analyzed data from twenty orbits of the Galileo spacecraft around Jupiter to confirm the suggestion from earlier flyby encounters that 10-20 minute waves existed in the magnetosphere. These are believed to be global resonance modes. Pioneer and Voyager data were also used by Stephan Espinosa (IC) to investigate the Saturnian magnetic field. A bipolar perturbation with a period close to the planet's rotation rate suggested a tilt between the rotation and dipole axes. Other observations appear to have ruled this possibility out, so other causes still need to be considered. Simulations of quasi-perpendicular shocks were presented by Robert Lowe (Queen Mary and Westfield College) to consider the mechanism causing the electron accelerations that have been widely observed. Of particular interest was the formation of ripples in the density and the magnetic field moving along the shock ramp. Eleri Pryse (Aberystwyth) presented results from a multi-instrument study using ground-based radars and satellite over-passes to explore the summer time ionosphere during southward enhancements of the IMF. In addition to the progressive equatorward motion of the plasma signature, the abrupt equatorward boundary of the electron temperature observed by EISCAT could be a signature of reconnection.

Kathryn McWilliams (Leicester) made use of the overlapping CUTLASS HF radar beams to generate the first multi-dimensional measurements of the convection pattern in the ionospheric footprint of a flux transfer event. The motion of this newly connected flux tube was compared with the ionospheric convection velocity. The relative strengths and weaknesses of a range of ionospheric sounding techniques were assessed by Natalia Nastasyina (Brighton) given the inherent uncertainties in both equipment and propagation media. She demonstrated from retrieval theory that the errors for the 'ordinary' polarization mode of radio waves increases from the magnetic pole to the equator, whilst the opposite is true for the 'extra-ordinary' mode.

The third and final session of the day was chaired by Peter Cargill (IC). Geomagnetic storms were a topic of conversation back in December 1128 AD according to David Willis (Warwick). From a number of old manuscripts, six distinct events, though intermittent, coincided with the synodic solar-rotation period. The timing of the storm suggested the phase of the solar cycle was near a maximum, whereas such events are associated with the declining phase during the current epoch. Will Wykes (Warwick) solved the complete set of the relativistic Lorentz equations numerically for the interactions of high speed electrons and whistler mode waves to show that the resulting chaotic interactions provide a mechanism for enhanced phase space diffusion. Thus electrons trapped in the radiation belt have an effective means of entering the loss cone and precipitating into the upper atmosphere. Two presentations from Leicester University considered the response of the ionosphere to the Interplanetary Magnetic Field. Firstly, Tim Yeoman described simultaneous interhemispheric radar observations of nightside ionospheric electric fields. The inclined phase front of the IMF at that time resulted in some asymmetries in the atmospheric response during a substorm growth phase and a substorm psuedobreakup interval. Secondly, Stan Cowley described how distortions of the magnetospheric field induced by the azimuthal component of the IMF can modify the ionospheric flow in such a way as to account for the measurements made by the EISCAT radar.

Matthew Denton (Sheffield) made use of the Sheffield University Plasmasphere Ionosphere Model to interpret observations from a DMSP satellite. Of particular interest was the question of whether readjustment of the neutral wind circulation or refilling of flux tubes was the dominant recovery mechanism following a geomagnetic storm. John Hargreaves (Lancaster) used the EISCAT VHF radar and the Kilpisjarvi imaging riometer to investigate a night-time precipitation event affecting the D-region of the ionosphere. A wave-like variation with a period of 25 minutes was almost certainly due to a pulsation in the particle fluxes, probably associated with high energy electron precipitation. A preliminary study of the magnetospheric data obtained from the Earth flyby of Cassini on its way to Saturn was given by Andrew Coates (MSSL). In addition to observing many of the expected boundaries and regions of the magnetosphere, there were a number of strange features including a narrow electron beam that required further investigation.

Roger Iles (MSSL) used data from two Defence Evaluation and Research Agency satellites to investigate the acceleration of relativistic electrons in the radiation belts. The acceleration process appeared to be related to solar wind speed, but less so to the intensity of the ring current. Two new experiments were introduced to the community to round off the meeting. Andy Lawrence (BAS) described a new auroral imaging system to be located at Halley, Antarctica early next year in order to investigate atmospheric gravity waves in the upper mesosphere and lower thermosphere region. In addition to providing a unique Southern Hemisphere dataset, it would allow inter-comparison with Northern Hemisphere observations. The first ever ground-based observations of the sunlit dayside aurora were reported by David Rees (Hovemere Ltd.). Sunlight overwhelms traditional detectors, but sophisticated optics have provided a means to investigate the low and mid-latitude thermosphere and ionosphere as well as the polar aurora during summer.

The meeting concluded with thanks to all the contributors, chairmen and organizer Andy Smith.

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